Abundance of moderate-redshift clusters in the Cold + Hot dark matter model

Y. P. Jing; L. Z. Fang

doi:10.1086/174582

paper

Abundance of moderate-redshift clusters in the Cold + Hot dark matter model

arXiv:astro-ph/9403012 · doi:10.1086/174582

Abstract

Using a set of $\pppm$ simulation which accurately treats the density evolution of two components of dark matter, we study the evolution of clusters in the Cold + Hot dark matter (CHDM) model. The mass function, the velocity dispersion function and the temperature function of clusters are calculated for four different epochs of $z \leq 0.5$ . We also use the simulation data to test the Press-Schechter expression of the halo abundance as a function of the velocity dispersion $σ_{v}$ . The model predictions are in good agreement with the observational data of local cluster abundances ( $z = 0$ ). We also tentatively compare the model with the Gunn and his collaborators' observation of rich clusters at $z \approx 0.8$ and with the x-ray luminous clusters at $z \approx 0.5$ of the {\it Einstein} Extended Medium Sensitivity Survey. The important feature of the model is the rapid formation of clusters in the near past: the abundances of clusters of $σ_v\ge 700\kms$ and of $σ_v\ge 1200 \kms$ at $z = 0.5$ are only 1/4 and 1/10 respectively of the present values ( $z = 0$ ). Ongoing ROSAT and AXAF surveys of distant clusters will provide sensitive tests to the model. The abundance of clusters at $z \approx 0.5$ would also be a good discriminator between the CHDM model and a low-density flat CDM model both of which show very similar clustering properties at $z = 0$ .

21 pages + 6 figures (uuencoded version of the PS files), Steward Preprints No. 1184

Abundance of moderate-redshift clusters in the Cold + Hot dark matter model

Abstract

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